Along with its needed effects, theophylline (the active ingredient contained in Theoclear-80) may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur while taking theophylline:

Some side effects of theophylline may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

For Healthcare Professionals

General

The majority of side effects have been dependent on the serum concentration. Generally, serum concentrations of theophylline (the active ingredient contained in Theoclear-80) ranging from 10 to 20 mcg/mL are considered therapeutic, and serum concentrations greater than 20 mcg/mL are associated with greater toxicity.[Ref]

There are several factors which may predispose a patient to higher serum concentrations and, thus, toxicity. These factors may include increased age, concomitant drugs which reduce the clearance of theophylline, hypothyroidism, congestive heart failure, liver disease, renal failure, and alterations in smoking habits. One series of patients with theophylline intoxication had recent upper respiratory tract infections.

The nature of acute toxicity of theophylline differs from chronic toxicity. Acute overdose is associated with higher theophylline concentrations and younger patients. In acute overdose the severity of toxicity is correlated with peak serum concentrations. Chronic overdosage is seen more commonly in older patients, and severe toxicity may occur with serum concentrations which are much lower than those seen in severe acute toxicity. In these patients, age is a predictor of severe toxicity.[Ref]

Gastrointestinal

Gastrointestinal side effects have included anorexia, nausea, vomiting, and abdominal pain. Theophylline (the active ingredient contained in Theoclear-80) may also cause locally-mediated gastrointestinal upset.[Ref]

Nervous system

Nervous system side effects have included generalized seizures, most commonly in patients with elevated serum concentrations, although seizures have occurred at therapeutic concentrations. Theophylline (the active ingredient contained in Theoclear-80) may also cause nervousness and tremor at therapeutic dosages, which become worse as serum concentrations increase.[Ref]

The mechanism of theophylline-induced seizures has not been determined. Seizures are generally focal with secondary generalization. Permanent neurologic deficits have been reported and morbidity may be high, especially in the elderly, patients with severe underlying disease, and patients with prolonged, uncontrolled seizure activity. The onset of seizures is not always preceded by less severe symptoms of theophylline toxicity. Patients with an abnormal neurologic history, including a history of seizures, cerebral infarct, or head trauma, may be predisposed to seizure activity. If theophylline is used in these types of patients, serum concentrations should be monitored closely and maintained in the low, therapeutic range.[Ref]

Theophylline serum concentrations have been a significant predictor of arrhythmias. One study reported multifocal atrial tachycardia in 8% and 16% of patients with a serum concentration between 10 and 20 mcg/mL and greater than 20 mcg/mL, respectively. The onset of serious arrhythmias is not always preceded by less severe signs of theophylline toxicity.

Elevated serum CK-MB levels have been associated with theophylline toxicity in the absence of cardiac disease. CK-MB levels have returned to normal following discontinuation of theophylline therapy.[Ref]

Metabolic

Metabolic side effects have included hypokalemia, hyperglycemia, respiratory alkalosis, hypophosphatemia, and hypomagnesemia, especially in the situation of acute overdosage. The magnitude of these abnormalities have been correlated with theophylline (the active ingredient contained in Theoclear-80) concentrations. Hypercalcemia has been reported in a patient with hyperthyroid disease with theophylline at therapeutic concentrations.[Ref]

In one group of patients with theophylline concentrations greater than 20 mcg/mL, hyperglycemia was present in approximately 50%, hypokalemia in 15%, and hypomagnesemia in 20%. Hyponatremia and hypophosphatemia were seen less frequently.[Ref]